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John Kerry (search) continued to ignore the competition as he campaigned as the presumptive nominee — with Tuesday's Wisconsin primary being a possible breaking point for his most vocal rival for the Democratic nomination, Howard Dean (search).

Though Dean continued to insist he would stay in the race no matter Tuesday's outcome, the seeming defection of his national campaign chairman to the Kerry camp seemed to indicate at least one member of his senior staff no longer believed a comeback for the former front-runner was in the cards.

"I will make it clear that I will do anything and everything I can to help him [Kerry] become the next president, and I will do anything and everything I can to build bridges with the Dean organization," Steve Grossman (search) told The New York Times in an interview published Monday.

Dean's national campaign manager, Roy Neel (search), echoed the belief that Grossman would soon join Kerry's campaign.

"He's made clear in his on-the-record comments to the press he has another agenda at work now," Neel said.

Dean himself would only confirm that Grossman had left his campaign, declining to specify how or why.

Dean's aides and political advisers have been telling Fox News that without a win in Wisconsin, his campaign is over and they would pack their bags.

For more on the campaign, click to view Foxnews.com's You Decide 2004 page.

Meanwhile, Kerry, who has a commanding lead in the race to oppose President Bush this fall, chided him for taking time out Sunday to attend the Daytona 500 (search), saying the country was bleeding jobs while he posed for a "photo opportunity." Bush had donned a racing jacket to officially open NASCAR's most prestigious event in front of some 180,000 fans.

"We don't need a president who just says, 'Gentlemen start your engines,"' Kerry said. "We need a president who says, 'America, let's start our economy and put people back to work."'

Kerry for the most part has chosen in recent days to aim his Campaign 2004 rhetoric directly at Bush as he has lapped his competitors, winning all but the South Carolina and Oklahoma delegate-selection contests.

His broadside against Bush came as the president argued anew against any rollback in the tax cuts that Congress has passed at his behest.

For his part John Edwards (search) declared "there are differences" with his Democratic rivals and said he was confident his campaign was gaining momentum. He said he would remain in the race well into March and the Super Tuesday round of electoral faceoffs.

Kerry's latest criticism of Bush came during a town hall meeting at Northcentral Technical College, where he toured the school's machine tool lab and posed for press pictures with students who engraved an 40-pound aluminum plaque with "Wisconsin Backs Kerry in 2004."

Lasee Philips, who is learning about the electrical and mechanical trades at the school, rose during the forum and told Kerry his support for the North American Free Trade Agreement (search) was "throwing some red flags in my mind."

After working 22 years as an injection molder in the same factory, Philips lost her job last year and blames the trade agreement.

Kerry responded that the United State initially gained jobs under NAFTA, but blamed subsequent losses on the failure to enforce side agreements on labor and environmental standards.

Philips was not convinced. "NAFTA, in my mind, sent our country in a tailspin the day it passed in 1997," she said after the forum. She said she hadn't decided who to vote for yet and would still consider Kerry.

Edwards claimed the endorsement of the Milwaukee Journal Sentinel, the state's largest newspaper. Then he sharpened his differences with rivals.

"I was against NAFTA," he said. "Governor Dean and Senator Kerry were for it. There are differences."

Polls have shown Kerry with a wide lead heading into Tuesday, but Edwards vowed to press ahead. While he has sought throughout the primary season to avoid attacking his rivals, Edwards said he would make differences clear and insisted there's plenty of time for voters to see those differences.

"It's not too late because this primary process is going well into March," said Edwards. "I want voters to know what the differences are between us."

Kerry said the first step to repairing the economy is to repeal Bush's tax cuts for people who make more than $200,000.

Bush, appearing in Florida on a visit that the White House characterized as official business, told an audience at a window factory: "You hear people in Washington saying, 'Oh let's not make the tax cuts permanent.' When you hear somebody say that, they're saying 'We're gonna tax you. We're gonna raise your taxes'."

Bush didn't mention Kerry by name. But a spokesman for the president, Scott Stanzel, said, "Senator Kerry's pledge to raise taxes on Americans is precisely the wrong thing to do."

Kerry later campaigned with fellow Massachusetts Sen. Edward Kennedy, who recalled visiting the state during his brother's campaign in 1960.

"Do for him what you did for my brother," Kennedy told a packed gym at the University of Wisconsin-Green Bay. "He'll be a great president."

In the Dean campaign, the departure of Grossman was the second high-level change in less than three weeks; campaign manager Joe Trippi was ousted in the wake of Dean's losses to Kerry in Iowa and New Hampshire.

It was during a brief question-and-answer session with reporters that Dean acknowledged Grossman had left, and just before the former Vermont governor was to appear at a campaign event in La Crosse, Wis.

He indicated that the move came following statements attributed to Grossman in which the chairman suggested Dean would likely curtail his campaign if he lost the Wisconsin primary.

Dean said he was appreciative of Grossman's efforts and that he had no hard feelings.

Grossman said he had neither resigned nor been asked to resign. But he said he understood why Dean considered him no longer part of the campaign.

"I think it's fair to assume my public statements and actions as tantamount to a resignation," said Grossman. "For the record, it didn't happen quite that way. I tried to make it clear I would do nothing prior to the end of the Wisconsin primary."

The so-far winless Dean insisted he was in the race for the long haul, although he has no formal post-Wisconsin plan.

"We're going to reassess. We're going to keep going, no matter what, because I think there are a lot of people all over this country who want to rebuild the party and rebuild America in a different way," Dean told Fox News Sunday. "And I think a lot of those people are delegates in New York and Illinois and beyond."

The Associated Press contributed to this report.